A bit of clarification:
* one bit per cell = two levels (SLC)
* two bits per cell = four levels (MLC)
* three bits per cell = eight levels (TLC)
* four bits per cell = sixteen freaking levels (QLC)
In the flash numbers game Western Digital's 3D, 64-layer NAND is being armed with 4bits/cell (quad-level cell, QLC) and bit-cost scaling (BiCS3) technology. WD's announcement follows joint-venture partner and legal war opponent Toshiba's QLC reveal in June. QLC flash chips have a third more cells and double the data density …
If it is guaranteed (and achieves) several complete drive writes per day and retention for several years then I do not care.
I thought the 4th bit per cell would not be worth the required over provisioning. Anyone want to bet on 32-level cell? Perhaps we will go in steps: 21, 23 and 26 levels are 4⅓, 4½ and 4⅔ bits per cell.
Do you actually require several complete drive writes per day? Most people think they do a lot more writing than they really do. Check the stats collected by your OS and you'll probably be shocked at how little writing you actually do versus how much you think you do.
I have looked, and I wasn't shocked. The percentage of my flash drives written per month is utterly pathetic compared to what they are capable of in a day. My oldest two have been in use for nearly a decade and are still not giving SMART warnings. Recording video continuously gets close to the limit of a small SSD, and parts of a data centre can require the specs of a big SSD.
The point I was trying to make is that switching QLC does not make me nervous at all. A drop in the specs would catch my attention. I hope it would hit the news hard, just like I hope that shingled spinning drives sold without warning of the performance hit would also be major news.
About 764 billion times bigger in fact.
It's also enormously faster and probably not far off the power consumption of that single chip.
Is there any other field that's progressed that much in that short a time span (even aircraft flight speed)?
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